Ion mobility spectrometer chamber

ABSTRACT

A FAIMS ion mobility spectrometer chamber with a high repeatability of dimensions, permitting stable gas flow, mechanical rigidity, excellent thermal conductivity, and high temperature stability of gas flow. The heating resistor, ionizer electrodes, HV detector electrodes and collecting electrodes, and conducting contacts, are applied in the form of layers of precious metals on ceramic plates. The heating resistor is located on the outer surface of the top and bottom ceramic plate in the form of a resistive layer of ruthenium dioxide. On the inner surface of each of the top and bottom ceramic plates, there are gas ionizer electrodes in the form of a layer of radioactive nickel, HV electrodes and collecting electrodes, in the form of layers of gold. The conducting contacts are made of a palladium-silver layer, whereas on the edge surfaces of the ceramic plates there are edge contacts, which are made of silver paste.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of the priority filing date of PCT application no. PCT/PL2012/000033 filed on May 16, 2012 and published in WO 2012/158052 on Nov. 22, 2012. The earliest priority filing date claimed is May 17, 2011.

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND

This invention relates to a FAIMS (Field Asymmetric Ion Mobility Spectrometry) spectrometer chamber, a device intended to detect chemical contamination.

Modern spectrometer scanners detect and identify most organic substances regarded as highly toxic. Currently, the detection of highly toxic chemicals (chemical weapons and toxic industrial materials) is performed by detectors based on IMS technology (ion mobility spectrometry). These are typically classical spectrometers operating at a temperature of about 50° C., with high sensitivity, but not very high resolution, which in practice leads to false alarms. The indicator, after detecting chemical contamination, generates a warning signal, i.e. it activates a beep and light or sends a signal to activate user-defined devices, such as ventilation devices or alarm systems. The number of false alarms should be as low as possible, as this undermines confidence in the contamination detection system and may cause the unnecessary implementation of emergency procedures.

The IMS detector chamber is divided into two areas. The first is the area from the semi-permeable membrane to the injection grid, in which ionization takes place by a β- or α-radioactive source, the second is the drift area—from the injection grid to the collecting electrode. A high voltage (generally 1.5 kV to 3 kV) is applied to the grid in front of the radioactive source, while the metal rings from the source to the collecting electrode have ever lower potentials. The field is thus shaped so that the ions from the ionization area move in straight lines to the collecting electrode. Most gaseous substances have different rates of mobility, so the transit time of the ions through the drift area varies, allowing for their identification.

Currently there is much research being carried out into the improvement of the properties of devices used to detect contamination. One solution is the coupling of the classical ion mobility spectrometer with a spectrometer with a high intensity, high frequency transverse field—FAIMS in a cascade sequence. FAIMS technology is based on the phenomenon of the segregation of ions passing through the detector. The FAIMS detector is constructed of ceramic plates opposite each other to which high voltage is applied at high frequencies. Under the influence of the electric field created within the detector segregation takes place at the collecting electrode. The observed segregation of ions in the gas flowing through results from their varying mobility in fields of greater and lesser intensity. The mobility of the ions is dependent on mass, the charge of the ion and the velocity of the gas flow. Under the influence of an alternating electric field applied to the electrodes, ions whose mobility does not fulfill the conditions of stable flow through the detector are captured. Considering the dependence of the mobility of the ions from the particles migrating through the active interior of the spectrometer on the value of the compensated field, we are dealing with a type of ion filter. The structure of the hybrid FAIMS-1MS system is based on using the FAIMS spectrometer as the first step, but without the collecting electrode. It works on a principle similar to an ion trap. After passing through the ionization source, ions of the analyzed gas pass in to the ion trap, formed of two rectangular plates parallel to one another. Between the covers a high intensity field of over 10,000 [V/m] is applied. Thanks to the fact that the mobility of the ions is dependent on the electric field, ion separation can be achieved, since the electric field in the ion trap can be shaped such that only selected ions reach the collecting electrode.

FAIMS spectrometers are approximately 10 times as sensitive, furthermore, they permit the separation of gaseous substances such as acetone, benzene and toluene, which to date have not been differentiated by classical IMS spectrometers, even those with high resolution.

An important factor in the operating of FAIMS spectrometers, omitted in scientific reports or patent descriptions, is the temperature stability of the gas flow. The temperature of the gas has a significant effect on the mobility of the ions, thus it has an effect on the location of the electrical peaks arising from different gaseous substances.

The construction of such closed chambers in glass systems is known, allowing for high purity in the chamber, but unfortunately such systems do not ensure the appropriate temperature stability of the gas flow.

The aim of the invention was to develop a chamber in which the drawbacks of current devices have been eliminated.

SUMMARY

The essence of the FAIMS ion mobility spectrometer chamber in this invention, comprising an inlet and outlet for the analyzed gas, heating resistors, a gas flow ionizer, FAIMS detector and ionic current collecting electrodes, where the FAIMS detector comprises two electrodes separated by a gap, to which a high voltage high frequency current is connected, is that the heating resistors, the ionizer electrodes, the detector electrodes and the collecting electrodes, as well as the conducting contacts, are applied in the form of layers of precious metals on ceramic plates. The heating resistors are located on the outer surface of the ceramic plates, in the form of a resistive layer of ruthenium dioxide. On the inner surfaces of the top and bottom ceramic plate, sequentially, starting from the inlet of the gas into the chamber, there are gas ionizer electrodes in the form of layers of radioactive nickel, HV and collecting electrodes in the form of layers of gold. The conducting contacts are made of a palladium-silver layer. On the side edges of the ceramic plates there are edge contacts that are made of layers of silver.

Such a chamber has high repeatability of dimensions, permitting stable gas flow, mechanical rigidity, excellent thermal conductivity and high temperature stability of gas flow, resulting in the analyzed gas being of the same temperature throughout the chamber and the ability to produce a very strong electric field inside. The use of layers of precious metals on the electrodes and detection surfaces fully protects the instrument from corrosion and enables long-term, stable operation, without any changes in parameters.

DRAWINGS

The chamber is shown in an example of the realization of this invention in the drawings where

FIG. 1 shows a perspective view of the chamber,

FIG. 2—a view of the outer surface of the top plate, and

FIG. 3—a view of the inner surface of the top plate, identical to the view of the inner surface of the bottom plate.

DETAILED DESCRIPTION

The spectrometer chamber with the inlet 1 and outlet 2 of the analyzed gas is constructed from four ceramic plates, the top plate 3, the bottom plate 4 and two interstitial plates 5 and 6, ensuring the air-tightness of the chamber and a constant distance between the top and bottom plates. The ceramic plates are made of 96% Al₂O₃ alumina. The top and bottom plates have a thickness of 1/40″, and the interstitial plates − 1/100″. On the outer surface of each of the top 3 and bottom 4 ceramic plates, there is a heating resistor 7 and temperature sensor 8. The heating resistor 7 constitutes a resistive layer of ruthenium dioxide paste, applied onto the ceramic plate. Above the resistor there is an electronic plate with an amplifier 9.

On each of the top 3 and bottom 4 ceramic plates on their inner surfaces there are, sequentially, starting from the gas inlet: ionizer electrodes 10, HV electrodes 11 and collecting electrodes 12. The ionizer electrode, in the form of a layer of radioactive Ni 63, is applied on a base of gold paste applied to the ceramic plate. Both the HV electrodes and the collecting electrodes are made of gold past. The conducting contacts 13, 14 and 15 are made of palladium-silver paste and the edge contacts 16 are made of silver paste.

After applying the above features onto the top plate 3 and the bottom plate 4, the two plates are bonded together with the interstitial plates 5 and 6 with low-melting sealing glass 17 at a temperature of 560° to 620° at a pressure of 8N to 12N, obtaining a monolithic, sealed chamber of a shape in accordance with the assumptions. 

1-22. (canceled)
 23. A system of analysis, comprising one gas chromatograph for the mutual separation of gaseous species, preferably but not exclusively, from a drilling mud, one oxidation oven for the heating of said separated gaseous species and the consequent production of at least one other at least partially gaseous species; one sampler for collecting and concentrating said gaseous species produced by heating in said oxidation oven, one laser isotopes analyser configured to analyse said gaseous species produced by heating, and at least one processor, wherein said gas chromatograph comprises: a sample valve provided with at least six ways, said sample valve being able to take at least a first configuration and a second configuration, different pairs of ways being placed in contacts according with said first configuration and second configuration; a storage valve provided with at least four ways, said storage valve being able to take at least two configurations; a final valve provided with at least four ways, said final valve being able to take at least two configurations; a gas entry line conduit, for the entry of a gaseous mixture to be analysed, said gas entry line conduit being connected to a first way of said sample valve; a sampling cell conduit, connected to a second way of said sample valve and to a third way of said sample valve; a backwashing column conduit, connected to a fourth way of said sample valve and to a fifth way of said sample valve; an intermediate line conduit, connected to a sixth way of said sample valve and to a first way of said storage valve; a store column conduit, connected to a second way of said storage valve and to a third way of said storage valve; a connection line conduit, connected to a fourth way of said storage valve and to a first way of said final valve; a holding chamber conduit, connected to a second way of said final valve and to a third way of said final valve; an exit line conduit, for the exit of each gas species travelling towards said oxidation oven, said exit line conduit being connected to a fourth way of said final valve and to said oxidation oven; and wherein said at least one processor is programmed to: control said valves and said conduits; synchronize a change of configurations of said valves; control said sampler for collecting and concentrating said gaseous species produced by heating in said oxidation oven; and analyse signals from said laser isotopes analyser.
 24. The system of analysis according to claim 23, further comprising: a first solenoid valve for controlling, via pressurized air, the sample valve; a second solenoid valve for controlling, via pressurized air, the storage valve; a third solenoid valve for controlling, via pressurized air, the final valve.
 25. The system of analysis according to claim 23, wherein said sample valve is provided with ten ways; and said gas chromatograph further comprises: a primary entry line conduit for entry of at least a carrier gas, said primary entry line being connected to a seventh way of said sample valve; a compensation conduit, for compensation of load losses of the carrier gas, said compensation conduit being connected to said primary entry line and to an eighth way of said sample valve; a conduit for discharge of the carrier gas, connected to a ninth way of said sample valve; a conduit for discharge of said gaseous mixture, connected to a tenth way of said sample valve; and wherein said at least one processor is programmed to control said primary entry line conduit, said conduit for discharge of gaseous mixture and said conduit for discharge of the carrier gas.
 26. The system of analysis according to claim 25 wherein said sample valve is able to place in communication at least: said sampling cell conduit at least with said gas entry line conduit and said conduit for discharge of said gaseous mixture; and said backwashing column conduit at least with said primary entry line conduit and with said conduit for discharge of carrier gas; when said sample valve is in said first configuration, or said sampling cell conduit at least with said backwashing column conduit and said primary entry line conduit; and said backwashing column conduit at least with said intermediate line conduit, when said sample valve is in said second configuration.
 27. The system of analysis according to the claim 26, wherein said storage valve is provided with six ways and two at least partially closed sections; and wherein said gas chromatograph further comprises a tap valve connected to a fifth way of said storage valve and to a sixth way of said storage valve.
 28. The system of analysis according to the claim 27 wherein said storage valve is able to place in communication at least: said store column conduit at least with said intermediate line conduit and said connection line conduit when said storage valve is in said second configuration, or said store column conduit at least with said at least two partially closed sections is in said first configuration.
 29. The system of analysis, according to the claim 28, wherein said final valve is provided with six ways; and wherein said gas chromatograph further comprises: a secondary entry line conduit for entry of the carrier gas, said secondary entry line conduit being connected to a fifth way of said final valve; and a discharge line conduit for discharge of the carrier gas, said discharge line conduit being connected to a sixth way of said final valve.
 30. The system of analysis, according to claim 29 wherein said final valve is able to place in communication at least: said holding chamber at least with said connection line and said discharge line, when said final valve is in said second configuration; or said holding chamber at least with said secondary entry line and said exit line, when said final valve is in said first configuration; and wherein said at least one processor is programmed to control said secondary entry line and said discharge line.
 31. The system of analysis according to claim 23, wherein: said oxidation oven transforms said each gas species to be analysed, at least into carbon dioxide CO₂ by heating; said sampler collects and concentrates the carbon dioxide CO₂; said laser isotopes analyser is configured to analyse the isotopes of carbon contained in the carbon dioxide CO₂; and said gas chromatograph is connected to at least one flame ionization detector for measuring gas species retention times and to calibrate the system of analysis. 